


Xrossover B10 x LoS

by DMChumble



Series: Xrossover Collection [5]
Category: Ben 10 Series, Legion of Super Heroes - All Media Types
Genre: Crime Fighting, Hero Vs Hero, New Transformation, Original Character(s), Superheroes, Supervillains
Language: English
Status: Completed
Published: 2020-11-28
Updated: 2020-11-28
Packaged: 2021-03-09 20:34:47
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 4
Words: 5,070
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27762331
Author URL: https://archiveofourown.org/users/DMChumble/pseuds/DMChumble
Summary: All stories with Xrossover in the title all tie together, but can be read individually as well. This one is Legion of Superheroes. I hope you all enjoy the story. I had decided to try writing Crossover Stories for awhile instead of the usual stuff I write since it was a new challenge for me, and decided to share it here too.
Series: Xrossover Collection [5]
Series URL: https://archiveofourown.org/series/2027191
Kudos: 1





	1. Chapter 1

Xrossover   
B10 x LoS Chapter 1

Ben and Gwen were traveling with Professor Paradox through the dimensional space to go on to the next location they would be needing to get to in order to continue helping other worlds in need. They were headed off to a place that interested Gwen as they had magical creatures sealed in amulets, though Ben was interested he didn't show the level of excitement Gwen did. 

"I'm curious to see what these creatures are going to look like, are there some that are the same, or are they all different?" Gwen then spoke wanting to know more about where they were supposed to be headed. 

"I'm sure you'll find out once we get there." Ben spoke in response as they continued traveling. "Be_id_s th_r_s Plent.." The Ultimatrix Wielder spoke as he began fading out as if signal was cutting out between them and his body was starting to glow the same way a hologram getting interfearnce was. 

"BEN!" Paradox called out reaching for the young hero, but it was too late he'd faded out of their sight. 

"What do we do?" Asked Ben's cousin as she was worried about what exactly they were supposed to do with Ben fading out like that, it was clear she was worried but trying to remain composed. 

"Relax, calm down, We just lost him to another timeline, You go to where I was intending to take you, and I will find Ben and bring him to you." The time traveling hero told her as Gwen nodded and Paradox took her to where they were supposed to go in the first place. 

While Paradox was taking Gwen to where they were supposed to go a strange machine was glowing and seemingly malfunctioning making crackling and whirrling sounds before Ben was then launched out of it and crashing into some office furniture nearby. He'd groaned from the pain and slowly stood up looking around confused as to where he was and saw some people dressed in costumes worn by superheroes, or maybe supervillains, he'd find out before doing something stupid. 

"Who are you?" He questioned them confused as to who these people were that abducted him. "What's going on?" 

"Easy there, I apologize but we were trying to get help from some heroes from our past, the device was meant to draw them at random and you were the one who was brough here." One of them spoke in response apologizing for abducting Ben. "I am Brainiac Five, A Bio Organic trying to make up for the sins of my ancest the first Brianiac. 

"I can vouch for them, my name is Lightning Lad, we need help in taking down a group that took the entire legion of superheroes to take down." The second person spoke introducing theirself as Lightning Lad to Ben not knowing which hero they'd managed to call upon. "And you are?" 

"Name's Ben, hero name Ben 10." The Ultimatrix M.U. Wielder told them as the Ultimatrix dial popped up and spoke saying 'unknown genetic samples aquired, two new transformations available' meaning they'd scanned both Lightning Lad and Brainiac 5. "What heroes of the past are you talking about? The Justice League, or Big Hero 6?" 

"Never heard of Big Hero 6, the Justice League are the heroes of the past." The one known as Lightning Lad spoke in response saying they were trying to get help from the Justice League so that they could fight some bad guys that took their entire legion to capture. "Did you say Ben 10?" 

"Um, ya.. Why?" Ben then questioned them asking why exactly that was important that he'd introducted himself as Ben 10 exactly. He wasn't really sure given their confused reaction. 

"Ben 10 is a myth. He supposedly showed up for a few months, swallowed the Anti Life Equation, and then dissappeared never to be heard from again." The hero in the blue and gold outfit stated saying that Ben was considered to be nothing but a myth to the rest of the world. 

"I can assure you I'm real." He spoke in response to the statement saying that he's very much real, and not a Myth at all. "This is the Ultimatrix." He stated holding up his arm that had the alien technology attached to it. 

"Ya right, if you really are Ben 10 then prove it." Lightning Lad spoke charging up his fists with electricity ready for a fight and wanting to prove that he really is Ben 10 and not some person randomly brought to them and charged towards him. 

Ben ducked out of the way and rolled to one side before poping up the dial on the Ulimatrix and slamming it down. In an almost blinding green light, he'd changed into a blue jellyfish like alien with 6 tentacles floating around in the air. He has white lines all over his body resembling lightning streaks with the Ultimaitrix located on his face and had golden bands near the tips of his transformation's tentacles. It'd surprised them at first but still tried to attack him. 

"AmpFibian." The strange creature called out ready to fight Lightning Lad, and the future hero shot electricity at him to which the creature absorbed the energy with his eyes looking smugly at him. "Nice trick, let me show you real juice." He then spoke and began charging energy with four of his tentacles and blasting him with electricity. 

Lighting Lad cried out in pain and collapsed to the floor from the blast and coughed. "Okay, ow. Maybe you really are Ben 10." He then spoke slowly trying to get up. 

"Enough, we should be fighting the Fatal Five, not each other." Brainiac 5 spoke saying that they should stop fighting one another because they needed to battle the bad guys. 

AmpFibian nodded and using one of his tentacles he slapped the Ultimatrix symbol changing back into Ben as the Techno Organic began to explain to him about the fatal five, who are the group of villains that they were having a hard time defeating. They'd need his help to take them on because it took the entire legion of superheores team to beat them last time and now they were spread too thin to do that again. 

"Doesn't sound too bad honestly, I've faced worse than that." Ben told Brainac 5 after hearing the descriptions of the villains which surprised them. 

"Well for us they are dangerous and we need to take them down before they cause any more trouble for the citizens of New Metropolis." Lightning Lad spoke saying that they needed help to take them down becuase for them they were a threat. 

"Right, so let's go stop them then." The Ultimatrix M.U. Wielder spoke saying they should just go and deal with the bad guys now. "The sooner we stop them the sooner the innocent civilians are safe." 


	2. Chapter 2

Xrossover   
B10 x LoS Chapter 2

Ben and the two Legionairs that used the tech to get him to their time headed out to go deal with the fatal five and meet up with other Legionairs that he hasn't met yet. Once they got there he was introduced to Bouncing Boy, Saturn Girl, Triplicate Girl, and Phantom Girl. He'd found the names to be lackluster but decided not to say anything until after they beat the Fatal Five. 

"So the one that's the most dangerous would be the Emerald Empress because of that eye?" Ben questioned the group asking that was correct with the Emerald Empress being the leader and most dangerous. 

"Yes, we'll need to find a way to take them down to diminish their power, then we'll have to take out the heavy hitters Validus and Persuader." Brainiac 5 stated in response about the plan to take them down to which Ben nodded. 

"But we also have to watch out for Validus and Mono, especially Mono, he can disintegrate anything he touchest." Lightning Lad then added to the statement about the bad guys they were about to fight warning of Mono. "But physically he can't take much punishment." 

"Right, so first focus on taking down Mono since his hacks ability is dangerous and we don't want any civilians being caught in that, then take out Validus to dwindle their numbers since he'd be the easiest to take down." Ben then told the others saying to handle them first to make things easier. "I'll take down the empress and that eye of hers, then we'll converge on Tharok and Persuader to take them down." 

"Who put you in charge?" The Electric based hero then asked getting Mad that Ben was acting like he was leading this team, especially since he was the least experienced with fighting the Fatal Five. 

"I put myself in charge." The Ultimatrix Wielder stated to Lightning Lad glaring him down unblinking as the two prepared for a fight. "You so much as sneeze without my okay you will regret it." 

"Oh ya? That I'ld like to s.." They began to say but Ben struck them in the face with his fist hitting him hard enough he fell over and was knocked stupid. 

Bouncing Boy began laughing about the fact that all it took was one hit to take out Lightning Lad. "One punch, serioulsy, only one punch." 

"Get him on his feet." Ben spoke telling the others to get Lightning Lad up with which Brainiac 5 stood him up and gently smacked his face snapping him out of it. "I've trained with the best of the best, trust me on this."

"Logically Ben's plan is the most sound and has the highest chance of succsess." The Techno Organic humanoid stated telling them that his plan is the best one they've had so far to deal with them. 

"Maybe so but you didn't have to hit me that hard." Lightning Lad complained while rolling his tongue around in his mouth then reached in and pulled out a tooth and spat blood onto the pavement. "Look you knocked out a tooth." 

"My bad." Apologized the Ultimatrix M.U. Wielder apologizing to them for knocking out the tooth. "I wasn't trying to hit you that hard." 

"Whatever, let's just go take them down." Spoke the lightning themed hero saying they should just go take down the fatal five. "According to the Science Police they are headed this way." 

Nodding Ben and the others began heading to the direction of the Fatal five's location. The Fatal Five were tearing a path through the city while making their way to the Legion of Superheroes while also breaking through the science police. The Legionairs began getting into a fighting stance while Ben began dialing up something on his Ultimatrix M.U. looking for something specific and finally found it just as the fatal five was noticing them just as he hit the watch and changed into Ultimate Upchuck. 

"Well if it isn't the Legion of Superheroes, and who's this? Some new guy? Not that it will help you." The Emerald Empress asked laughing seeing Ultimate Upchuck. "That thing is even fatter than your blue boy that becomes a ball." She continued to laugh. 

While they were laughing Ultimate Upchuck shot out long tongues that wrapped around the Emerald Eye and pulled it towards the Legion and was swalloweld whole in one single gulp, he then licked his lips and spoke. "Delicious, so you were saying?" He spoke as the eye dissolved into the stomach of the creature and gave it a strange emerald glow.

`Boss I think this might be a trap." Mano, the being with the black skull for a face with purple helmet and yellow outfit, spoke stating that this seemed like a trap given that that thing in front of them currently just swallowed the Emerald Eye, which was their most powerful weapon. 

"You think? Tell you what, how about an Eye for an Eye?" Ultimate Upchuck questioned before hitting the Ultimatrix M.U. Symbol and changed into a creature who's upper-body is covered with green eyes everywhere except for his face, which consists of a mouth and a very large pair of bat-like ears. They had dark yellow skin with lighter yellow skin on his chest and feet. He also had eyes on the palms of his hands which had three fingers and a thumb on them. His feet were three toed and the toes were more like claws. He also wore a green belt with the Ultimatix M. U. symbol located on a single armored shoulder pad with one big eye in the center of his back. His pants were black with white patches where the knees were located, and he wore green cuffs on his wrists and ankles. "EYE GUY!" 

"What the heck is that thing?" Tharok questioned seeing Eye guy and watching as they fired energy beams out of the eyes in the palms of their hands and dodging. "Whatever it is it's not going to be a ble to stop us." 

"Oh Eye think Eye will." The alien hero retorted running over to a street light and grabbing it, ripping it out of the ground and using it as a bat, though Tharok managed to avoid it Emerald Empress wasn't so lucky without the Emerald Eye she wasn't much of a threat and got knocked into an information booth. 

Can you not make those aweful eye puns?" Saturn Girl questioned him asking if there was a way he wouldn't be making those bad puns, and instead focus on helping them fight the fatal five.

"Eye just can't help myself, Eye Guy's Puns just get Cornea and Cornea." He then joked in response which made literally everyone roll their eyes, and while they were doing so Eye Guy closed all his eyes and made a large one in the middle of his chest jut out on a stem growing larger and blasting Mano with a massive blast of energy taking them out of the battle before they knew it was happeneing. 

"Did.. Did he just use puns as a weapon?" Phantom Girl questioned confused as to what exactly just happened, all she knew was an energy blast took out Mano while they were all rolling their eyes at the bad jokes that were made by the alien. 

"That's exactly what Eye did." They laughed in response before being blasted backwards by Tharok using his blaster arm finally having enough of the bad jokes. 

"NO MORE PUNS!" He then yelled at the alien hero really annoyed and then they all began to fight the Legion again, but they were down to only three of five members with the other two taken out. "Or can I just go by Ben 10, that's what I always went by as my Superhero name." 


	3. Chapter 3

Xrossover   
B10 x LoS Chapter 3

Tharock had blasted Ben who had currently been transformed into Eye Guy because of all the bad puns he had been making. Still, he'd managed to take the Fatal Five down to only three members before he'd been shot. The Legionairs looked worred as he'd been covered in some debris and thought he'd possibly been seriously injured. But Suddenly there was an almost blinding green flash that was peeking through the rubble before a twelve foot tall Red alien creature with two sets of arms burst out of it. 

"FOURARMS!" The New alien called out and then picked up the debris with easy. "Now It's my turn." He stated to them with a smirk and threw the debris at him while the villain began blasting at them. 

"You should have stayed down, we're going to destory you." Tharock called out blasting at Fourarms not understanding how basically screwed he was. 

"Ya, like I haven't heard that line before." He stated with a sigh while avoiding and deflecting the blasts with the metal bands on his wrists. "You'd think bad guys would get some new material after a thousand years or so." 

While he was dealing with Thayrock Brainiac 5 and Lightning Lad blasted Persuader who was trying to sneak up on him. "We got your back just take him down." Lightning Lad called out to Fourarms who nodded in response and cracked his knuckles. 

The cybernetic villain continued blasting at Fourarms who went back to deflecting the attack with the bands on his arms and then began running towards them. "Go Down already!" He called making his shots stronger while they were being deflected. 

"Sorry, but that's not happening." Spoke the red multi limbed creature as he grabbed the cybernetic villain. He used his upper arms to pick him up while using his lower arms to grab the blaster by the elbow and snapping it off completely ripping it from their arm.

Everyone stopped when they heard Tharok cry out in pain of having his cybernetic blaster arm ripped off by Fourarms. Taking advantage of this situation he then threw Tharok head first into Persuader which made the two of them collide and made Persuader drop his Axe from having one of his allies slammed into him like a projectile. Fourarms then struck the Ultimatrix Symbol and changed into a large human-sized crab that was orangish red in color. He had pale yellow eyes with black outlines on them, all his joints seemed to be wrapped in black bands as well. His hands are large pincer claws and his head had a split down the middle with some sort of brace that was black and green in color. The two split pieces of his head had black lines similar in shape to lightning bolts on it, and the center of his fourhead just above the line for his eyes had the Ultimatrix M.U. Symbol located on it. 

"BRAINSTORM!" The crablike creature called out opening the hatches on his head and generating lightning before blasting the visible brain hidden behind a clear see through material of Validus, it caused his brain to glow green in color as Brainstorm closed his head hatches. "Now I believe the simple venacular statement would be, get them." He spoke pinching his claws and gesturing to Persuader as the giant monster roared out and slamed him down into the ground with a big crushing fist. 

Everyone was surprised when he'd turned into a crab and taken control of Validus, but soon snapped out of it after the monster took out Persuader. "Phantom Girl to the Science Police, we have the fatal five subdued, please send out a team to come get them." The girl in white spoke into a com to let the science police know that it was over. 

"Yes, now It would seem that the Legion of Superheroes don't have very creative superhero names." Brainstorm then spoke while they were waiting for the science police. "For example, Bouncing Boy could call himself Ricochet, which referrs to bouncing off of things, and Triplicate Girl could refer to herself as Trinity which means to be made up of Three." 

"Hey thats... That's better actually." Bouncing Boy spoke seriously thinking about it since it did sound cooler to him, but decided against it since everyone already knew him as Bouncing Boy. The others were going to say something, but the science police then showed up. 

"Ah, the local law enforcements referred to by the legion of superheroes as the Science Police. It is a pleasure to make your aquaintance, please place these rogues into the proper confinements immediately, and I do so sincerely hope that you have shackles large enough to contain this rather large individual." Brainstorm spoke seeing the Science Police and asking them if they had cuffs big enough to fit Validus, thankfully they did. 

Once all the fatal five were taken away the Legion began to head back to their base with Brainstorm following them. They wondered why exactly he hadn't changed back but didn't question it aloud as the crablike alien continued onward. After getting back he did change back into Ben and stretched out wandering around the area while waiting for Paradox to come and get him figuring they'd be there soon probably. 

The Legionairs looked confused and Phantom Girl spoke up. "Okay, first, why did you stay the giant crab alien, second, what are you looking around for?" She questioned him as she and the others waited for his answer. 

"Usually if I change back into Ben I get swarmed by fangirls, it's.. honestly kind of annoying." Ben then answered as to why exactly he didn't change back until after they got back to the Legionaire base. "As for why I'm looking around, I'm waiting for Professor Paradox to come pick me up." 

"Well, after what we've seen today, we could use you in the Legion." Lightning Lad stated to him saying that they could use someone like him as a part of their team. "That is if the rest of the league agrees." 

"What are you going to have a vote or something?" Ben questioned hearing that as the Legion members nodded to let him know that's how they do it. 

"That's exactly what we do." Bouncing Boy told him speaking up as they were all going to the voting area to see if Ben should join them or not. They were probably going to all vote yes anyway, it was a formality at this point in his eyes. 

The Legion members were all going over to the voting machines while they had other legionairs that were off world at the moment on holo screens placing their own votes as well. They all took their time weighing the pros and cons of him joining them and placed their votes one by one little by little, and soon they had all placed their votes. 

"Well, looks like majority vote rules, the Legion thinks you'd make a good member of the team." Lightning Lad spoke up Telling Ben that they decided he should join them. 

"Does that Mean I have to come up with some sort of lame superhero name?" Ben then joked asking them if he had to come up with a Leion Superhero name. 


	4. Chapter 4

Xrossover   
B10 x LoS Chapter 4

The Legion of Superhero had voted on whether or not to allow Ben to join their ranks as a new heroe, though they had known that Ben would have to leave eventually they voted to give him hero status in the Legion. He'd been trying to come up with a new design for a costume because they wouldn't shut up about having to make one. He refused to go with anything that resembled spandex because he didn't like it. 

"So, have you decided on what you want your outfit to be like?" Bouncing Boy questioned Ben asking if he'd made a decision yet for his new Legion of Superheros costume that he'd be wearing to join them. 

"Actually ya, it's almost done." Ben answered in response as he was just adding the finishing touch. "Once I've got it done I'll do the pledge after that I dunno what's going to happen." He stated to Bouncing Boy who nodded and headed on off down to the others to let them know what Ben said to him. 

Ben just put the final touches on the outfit and was now getting it made to fit him with their future tech synthesizing what he'd wanted it made out of. Starting with the boots they were metal but felxible so that it wouldn't hinder movement, made of some futuristic metals he didn't really know how to pronounce the names of the foot covering part was silver in coler with the upper foot part being grayish black and above that at the ankle and just a bit upwards of it being golden in color with a little clock attached to a small latching handle on the left boot. The rest was a leather like material with buttons on it being wrapped around his leg with his pants being tucked in, the leather part went up to just a little below the knee. The pants were a jean-like materal with a large parachute pocket on the side of each leg and normal pockets up towards the waist area. Moving up a little further, he was wearing a white button up dress shirt with a victorian style button vest that was brown and the same material as the leather-like boot parts, along with a folded hankerchief in the vest's left breast pocket. The collar of the shirt was wide and folded down making it flare out a bit. Next He wore gloves that were the same color as the shirt that came up to just past his wrists and had a button on them as well. Covering him was a large dark green victorian style coat with the tail of the coat split in two along with the Omnitrix symbol on his back in the center of a bronze cog wheel. On the front on each side of the buttons was a stitched swirrling pattern like a thorn bush pattern. His right arm had a sleeve garter on it and on the left arm was a gold watch with wings pinned onto the side of it, just below the sleeve was a small amrband made to look like a belt put through loops on the sleeve. Finally the sleeves had elbow patches of the same leather-like material of the boots and vest, along with gold ring-framed goggle with green lenses and a futuristic elastic-like band resting atop his head. 

After FINALLY getting his costume ready Ben Went on down to the others who looked at his costume kind of confused as they'd never actually seen anything quite like it. For a long moment they were'n't able to say anything about it not knowing how to react, though Lightning Lad was the first to speak up after seeing Ben's new hero costume since all the others were a little too stunned to speak just yet. 

"What in the heck is that?" Lightning Lad questioned seeing the new costume that Ben had come up with for himself to join in the Legion of superheros. It was definately different than what he was used to. 

"Y'know not everyone is going to wear spandex." Ben then stated to them all in response to the young Winathian's question. "It's called Steampunk." 

"Brainy you know a lot of stuff, what's Steampunk?" Bouncing Boy then spoke up next curious to know just what the alien hero from the pas was referring to, though it seemed that the Coluan didn't have any idea. 

"Checking now, the databases are very old for this sort of thing." The Coluan known as Brainiac Five spoke in response to the question. "The first known appearance of the term steampunk was in 1987. It is a retrofuturistic subgenre of science fiction that that incorporates technology and aesthetic designs inspired by 19th-century industrial steam-powered machinery and often set in an alternative history of the Victorian era or the American Wild West where steam power remains in mainstream use." 

"In short it's designed to look like the clothes from the era of the steam engine." Ben simplified for them to help the Legion to understand what exactly his outfit was meant to be so that they could get on with the ceremony. 

"Yes of course." Saturn Girl was the next to speak up as they were getting back on track with the whole thing and getting Ben to be a member of the Legion of Superheroes officially. "Timberwolf, if you would please?" 

"Gladly." The animalistic hero answered with a nod walking over and opening the box that has a legionaire belt and ring on it. Which Ben then took and began to put on since he was supposed to do so for the ceremony. 

After taking the belt and Ring Ben then put them on and cleared his throat before holding up his hand that has the ring on it and began to speak. "To the Legion of Superheroes I make this solemn pledge: To use my powers for good. To fight for justice and protect the innocent. To aid my fellow Legionnaires in times of peril and to keep their secrets safe. I choose a new name to honor the heroes of the past. I am Ben 10."

"Well Said Ben." A familiar voice spoke from behind the alien hero as they were walking up to stand at his side, catching the legionaires completely off guard as he appeared without any of their alarms or sensors being triggered at all at the intrusion. "I like the new look." 

At the intruder's notice Lightning Lad fire off a blast of electricity since he had no idea if they were friend or foe, though the intruder did make him uncomfortable in some way, like he was way more dangerous then he looked. This kicked up dust around Ben and the intruder as he'd blasted part of the floor, though it was solid so there was nothing for them to fall through. Much to their surprise when the dust began to clear there was now what looked like a walking stone wall with all kinds of strange technology holding it together at the joints like disks with dark hair and a face that had the mouth and eyes completely see through as if looking through a mask. The Ultimatrix symbol was located on a metal band around their non exitent neck floating as if there was one to hold it in place, and there was a barrier around the new creature and the intruder. 

"RoadBlock." The new creature speakoke in a gravely and yet also Metallic Voice as they looked up at Lightning lad through their mask even though they didn't have any eyes. "Ready to calm down? This is Professor Paradox, he's a time traveling hero." The being known as Roadblock explained to them before letting down the barrier, since they had the symbol they recognized them as Ben. 

"That is correct. I've come to take Ben off to the next place that he is needed ." The man known as Professor Paradox stated while looking at his watch. "While I'd love to stay and chat we really must be going, ta ta everyone." When they closed the watch they were gone out of the sight of the legionaires leaving them to ponder the confusion of what exactly just happened. 


End file.
